Epitaxial Growth of Boron Carbide on 4H-SiC

Abstract

In this work, the successful heteroepitaxial growth of boron carbide (BxC) on 4H-SiC(0001) 4° off substrate using chemical vapor deposition (CVD) is reported. Towards this end, a two-step procedure was developed, involving the 4H-SiC substrate boridation under BCl3 precursor at 1200°C, followed by conventional CVD under BCl3 + C3H8 at 1600°C. Such a procedure allowed obtaining reproducibly monocrystalline (0001) oriented films of BxC with a step flow morphology at a growth rate of 1.9 µm/h. Without the boridation step, the layers are systematically polycrystalline. The study of the epitaxial growth mechanism shows that a monocrystalline BxC layer is formed after boridation but covered with a B- and Si-containing amorphous layer. Upon heating up to 1600°C, under pure H2 atmosphere, the amorphous layer was converted into epitaxial BxC and transient surface SiBx and Si crystallites. These crystallites disappear upon CVD growth.